Thermostat



Aug. 19, 1941. L. M PERsoNs THERMO S TAT Filed Deo. l, 1937 Patented Aug. 19, 1941 THERMOSTAT Lawrence M. Persons, St. Louis County, Mo., as-

signor to Automatic Control Corporation, St. Louis, Mo., a corporation of Delaware Application December 1, 1937, Serial No. 177,406

2 Claims.

The present invention relates generally to thermostats, and more particularly to a comtory means being available for absorbing fluid expansion resultant of ambient temperature without moving the several parts of the switch or other device being operated by the thermostat.

Therefore, an object of the present invention is to provide novel compensating means in combination with a thermostat.

Another object is to provide means for absorbing the expansion of the fluid of a solid-charge thermostat resultant of ambient temperature which is effective to prevent movement of the `diaphragm and switch parts, or the like, with which the thermostat is operatively associated, thereby eliminating inaccuracies of operationy of the switch, or other device.

Another object is to provide a thermostat including a cup having compensating means l adapted to reduce to a minimum movement of the associated diaphragm from causes other than expansion of the fluid due to the application of heat at the thermostat bulb.

Another object is to provide a simple and easily installed compensating means adapted to be used in combination with the cup of a solidcharge thermostat.

Other objects and advantages will be apparent from the following description, taken in conjunction with the accompanying drawing, in which: i

Fig. 1 is a top view of a solid-charge thermostat incorporating a preferred modification of the present invention;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. i; and,

Fig. 4 isa section taken similarly to the section shown in Fig. 3 through a solid-charge thermostat incorporating another preferred modification of the present invention.

Referring to the drawing more particularly by reference numerals, Figs. 1-3 show a solidcharge thermostat generally designated ill which .includes a bulb il, a tube i2, a cup i3, and a diaphragm i4. The cup i3 includes a conventional attaching fiangc i5 having the apertures I6 therein, an annular wall i1, and a circular face il. 'I'he diaphragm i4 is of cup shape, including a circular face i9 and an annular wall 20, and is nested `in the cup i3 (Figs. 2 and 3). An operated member 2l is shown disposed with one end abutting the inner side of the face i9 of the diaphragm I4 in the usual manner. A brass strip 22 of a configuration shown in` Figs. 1-3 is weldedor brazed to the outer side of the circular face il of the cup i3.

In Fig. 4 there is shown a second modification of the present invention. The several parts of the thermostat iii are identical with the parts described above and are identified with the same reference numerals.

A pear-shaped member 25 is welded or otherwise fixed to the annular wall of the cup I3, the member 25 being of continuous construction, although a skeleton construction can be made to function. The pear-shaped member 25 is of brass, or of other material which readily expands upon the application of heat.

A steel pin or shaft 26 is fixed at one end to the narrow portion of the pear-shaped member 25, as by welding 2l, and at the other end contacts the outer side of the face i8 of the cup i3. In constructing the modification shown in Fig. 4', the cup I3, the pear-shaped member 25, and the shaft 26 are assembled with the shaft 2B depressing the face i8 of the cup i3.

Operation As has been pointed out above, the strip 22 is of brass, or of other expanding material, while the cup i3 is of steel, a material which expands relatively much less readily than brass. When the temperature around the cup i3, the diaphragm I4, and the adjacent portion of the tube i 2 rises, the strip 22 expands and draws the circular face i8 of the cup |13 outwardly (to the left in Fig. 2) to permit the fluid between the cup i3 and diaphragm Il to expand without moving the diaphragm i4, and, therethrough, the vmember 2i, this expansion, of course, relating'only to that expansion resultant of the ambient temperature rise. The actual movement of the circular face i8 of the cup i 3 through the strip 22 compensate the expanding fluid. It is clear that such a compensating device materially aids in an accurate operation of the associated electric switch, or the like.

' Referring to Fig. 4, rise in the ambient temperature eects an expansion of the brass pearshaped member 25, which moves to the left in those portions remote from the cup I3 and carries with it the shaft 26, thereby relieving the pressure applied to the circular face I8 of the cup I3 by the shaft 26 and permitting this circular face I8 of the cup I3 to expand (to the left in Fig. 4) through its inherent penned up resiliency. Expansion-oi the circular face I8 of the cup I3 permits the fluid between the cup I3 and the diaphragm I 4 and within the adjacent portions of the tube I2 to expand without moving the diaphragm I4 and therethrough the `member 2|.

It is thus apparent that there has been provided compensating means for use' in combination with a solid-charge thermostat which is thoroughly eective and eiiicient .in producing a thermostat which has'a high degree of accuracy for actuating a switch or other associated mechanism.

It is to be understood that the foregoing description and accompanying vdrawing have been 'is, of course, very slight, but it is sufficient to given by way of illustration and example and not ior purposes of limitation, the invention being limited only by the claims which liollow.

What is claimed is:

1. In combination, a thermostat including a cup, a diaphragm within the cup, a pear-shaped member of expansible material fixed to the cup, and a shaft of material of a low coecient of expansion xed to the member and normally maintaining said cup under compression, said member and shaft comprising means to compensate for temperature changes in the medium surrounding the cup and diaphragm.

2. In combination, a thermostat including a cup and a diaphragm, a pear-shaped member xed to the cup, the wide part of said member being contiguous to the Wall of the cup, and a shaft Xed to said member at the latters narrow part and bearing at its free end against the face of the cup to normally maintain said face ander compression, s'aid member having a greater coeiicient of expansion than the shaft, said member and shaft being adapted to effect movement of the cup to compensate for change in volume of expansible medium Within the cup and diaphragm due to changesin ambient temperature.

LAWRENCE M. PERSONS. 

